Patent GB-155369-A (GB)
Title: Improvements relating to train speed controlling systems
IPC: B60T17/22
Filed: 1919-09-16
Abstract: 155,369. Belfield, R., (Westinghouse Air Brake Co.). Sept. 16, 1919. Fluid-pressure.-The brakes of train are automatically applied by a speed-responsive device at predetermined low, medium, or high speeds according to the position of a change-speed valve controlled by electro-magnetic valves energized from the track. General arrangement, Fig. 1. An application valve 15, fitted with differential pistons 10, 12, controls communication between the main reservoir 62 and driver's valve 3, and operates to vent the equalizing-reservoir 61 of the driver's valve into a reduction reservoir 65 so as to open the equalizing-reservoir discharge valve 105 to produce a venting of the train-pipe at the desired speed. The speed at which this may occur is regulated by the position of a change-speed valve 22 fitted with pistons 17, 18 and made to occupy a low, medium, or high speed position by means of track-controlled magnets 35, 38. The movement of the valve 15 to application position is effected by a centrifugal governor 24 operating a tappet plate to open one or more of the valves 27 - - 32, and its return to release position is effected, after a low-speed application, preferably by means of a hand-release valve 42, and after medium or high speed applications, by governor actuation of a valve 33 or 34 respectively. Automatic application. (1) At parts of the track where a low speed only is permissible, both magnets 35, 38 are de-energized and their valves 36, 37 and 39, 40 are in the position shown in Fig. 1, venting piston chamber 19 by way of ports 86 - - 89, and piston chamber 20 by ports 81 - - 85, so that the valve 22 is moved by mainreservoir pressure between the pistons 17. 18 to the position shown in Fig. 1. If the speed rises above the predetermined low value, the governor 24 opens first a low-speed lap valve 27 and then an application valve 28, thereby venting piston chamber 11 by ports 93, 94, 95 and valve 28, so that the valve 15 is moved by main-reservoir pressura under the piston 12 to the application position, Fig. 3. In this position, the communication 69, 70, Fig. 1, between the main reservoir and driver's valve is cut off, so that the automatic application cannot be interfered with by the driver, and the equalizing-reservoir 61 is vented to the reduction reservoir 65 by ports 59, 103, 67, Fig. 3, and the brakes applied. As the speed slows down, the governor first closes valve 28, but the valve 15 remains in application position since piston chamber 11 is still vented bv way of ports 93, 96, 111, Fig. 3, 116, 97, Fig. 1, and lap valve 27, thus ensuring that the desired trainpipe reduction shall occur. When the valve 27 closes, the valve 15 is moved to lap position, in which the equalizing-reservoir is cut off from the reduction reservoir and becomes re-charged, closing the discharge valve 105. The valve 15 remains in this position until release occurs as described below. (2) When the train enters a medium-speed zone, the magnet 38 is energized, closing valve 39 and opening valve 40, thereby cutting off the venting of piston chamber 19 and supplying it with main-reservoir pressure by port 113, valve 40, and ports 88, 87, 86, whereupon the valve 22 is moved to medium-speed position, Fig. 4, in which the ports 95, 97, Fig. 1, are blanked, so that no action takes place when the governor opens valve 27, 28. When, however, the speed rises above the medium limit, the lap and application valves 29, 30 are successively opened, the latter venting piston chamber 11 to atmosphere by ports 93, 117, 118, Fig. 4, causing the valve 15 to effect an application of the brakes as before. (3) On a high-speed part of the track, both magnets 35, 38 energized, closing valves 36, 39 and opening valves 37, 40, allowing main-reservoir air to flow to piston chamber 19 as before, and to piston chamber 20 by port 113, valve 37, and ports 84, 83, 82, 81, whereupon the valve 22 takes up a neutral or high-speed position. In this position, the passages to the valves 27 - - 30 are blanked, so that operation of the valve 15 does not occur until the speed rises above the high limit so that the valves 31, 32 are opened, whereupon piston chamber 11 is vented by port 93 and valve 32. Release. (1) After a low-speed application, manual operation of the tappet 42 opens valve 41 to vent piston chamber 13 by ports 109, 110, pipe 43, check valve 44, pipe 45, and ports 88, 89, so as to restqre the valve 15 to release position. (2) After a medium-speed application, the decrease in speed causes the governor 24 to open valve 33, which vents piston chamber 13 by ports 109, 114, 115, Fig. 4. (3) After a high-speed application, a similar venting of chamber 13 takes place past the valve 34.